共查询到17条相似文献，搜索用时 171 毫秒
1.
钱怀洲 《顺德职业技术学院学报》2010,8(3):8-10
利用热力学第二定律针对两种不同双级二氧化碳制冷系统进行[火用]分析。低温系统下二氧化碳双级压缩循环的[火用]分析表明节流阀的[火用]损失所占比例最大,而蒸发器[火用]损失所占比例最小。同时模拟计算结果表示低温系统下二氧化碳双级压缩循环存在一个最优的蒸发温度使其循环的[火用]效率最大。 相似文献
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本文采用火用分析法 ,对冷轧带钢的罩式炉热处理系统进行了能量分析 ,计算了热处理过程中的各种火用值、热量及系统火用效率 ,指出了系统用薄弱环节 ,并分析了用能薄弱环了的火用损失分布情况。分析结果为工艺用能改造提供了依据。 相似文献
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王寒栋 《深圳职业技术学院学报》2012,11(5):3-10
在一种太阳能驱动、采用喷雾吸收器并以板式换热器作为主要换热部件的LiNO3-NH3-He三工质扩散吸收式制冷系统中,根据试验测得的运行参数,以溶液的p-t-x西方程及物性方程、传热基础理论等为依据,提出了计算溶液换热器中溶液流量的方法,并利用综合传热系数k、传热单元数N_TU与换热器效率s研究了板式换热器作为LiN03-NH3-He扩散吸收式制冷系统发生器、冷凝器、溶液热交换器、溶液冷却器时的换热性能．试验与分析表明,板式换热器的换热面积及其内部流道中的流量（流速）对其综合传热性能具有较大影响;在介质流量一定时,板式换热器不宜考虑过大的面积预留量;板式溶液换热器内部流道宜采用多流程布置形式以强化传热、提高换热效率． 相似文献
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杨惠山 《泉州师范学院学报》2005,23(4):19-23
研究存在热阻和回热损失的斯特林热机的（火用）经济优化性能，得到一些新的性能参数，并揭示了它与生态学优化性能间的联系，所得结论可为斯特林热机的研制和优化设计提供新的理论指导。 相似文献
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板式换热器计算机模拟中采用的模拟算法有很多种,通过研究发现这些传统的数值迭代算法存在自身无法避免的缺陷。为克服这些缺陷,对遗传算法进行了研究,取得了将模拟问题中的数值迭代算法转化为最优化问题中的遗传算法的方法。通过实例模拟,符合实际情况,证明遗传算法在板式换热器模拟中是有效的、可靠的模拟算法。并通过对模拟结果的分析,绘制出了热、冷流体出口温度分别随热、冷流体流量变化的工况特性曲线图,直观地反映了板式换热器的工况特性,可为板式换热器最优化设计和动态分析提供技术依据。 相似文献
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文章介绍了海上石油钻井平台用钛制板式换热器的结构、特点及选型计算方法,分析了设计选型过程中的主要影响因素,并采用对数平均温差法对应用实例进行计算分析。 相似文献
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《实验室研究与探索》2013,(11):60-64
为探究板式换热器的换热性能,根据工程热力学、传热学、热工测试技术等基本测试原理和方法,结合现行的国家标准与规范要求,研制了板式换热器性能实验台。此实验台安装有高精度的传感器,并研发了基于STM32为主芯片的高精度数据采集板和上位机软件。上位机软件利用Visual Studio2008的开发环境,用C#编程语言编写完成,并结合了动态Flash、SQL Sever数据库、虚拟仪器等相关技术。根据实测数据,计算出板式换热器的性能参数和传热关联式。实验结果表明,该实验台具有自动化程度高、控制精度高、可操作性强等特点,为理论研究提供了可靠的实验依据和数据支撑。 相似文献
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徐[火勃]是晚明诗人、作家、藏书家。或由于文献资料的原因,此前对其生平的研究均是若明若暗,语焉不详。徐生平大致可以分为3个时期：30岁之前为第一个时期,31岁至57岁为第二个时期,58岁至72岁为第三个时期。第一时期,兄徐熥在世,徐[火勃]参与其复振闽中风雅的活动;第二时期,刊刻《鳌峰集》二十八卷;第三个时期,与曹学佺主闽中文坛。 相似文献
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由于古代赫哲族的社会发展落后以及受生产方式的制约,使得在很长一段时间内,赫哲族对火的认识是很蒙昧的。由于火的威力强大,赫哲族对火产生了崇敬信仰,尊其为火神;同时由于火的破坏力强,赫哲族对火又产生强烈的敬畏之情,因此对火产生了许多禁忌。为了更好地使用火,赫哲族学会了如何取火和存火,用火更为方便。由于掌握了这些用火技术,使赫哲族对于火的使用范围更加广泛,这对促进赫哲族社会的发展具有重要影响。 相似文献
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分析了换热器对集热器效率的影响,确定了换热器对集热器的削弱因子;提出了二次换热平板型太阳热水系统的能量方程。对自然循环二次换热平板型太阳热水系统系统的热性能进行了测试与分析,测试表明,自然循环二次换热平板型太阳热水器的平均日效率低于普通平板型太阳热水器,但高于真空管太阳热水器。 相似文献
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In order to identify the locations of irreversible loss within the transcritical carbon dioxide refrigeration cycle with an expansion turbine, a method with respect to the second law of thermodynamics based on exergy analysis model is applied. The effects of heat rejection pressures, outlet temperatures of gas cooler and evaporating temperatures on the exergy loss, exergy efficiency and the coefficient of performance (COP) of the expansion turbine cycle are analyzed. It is found that the great percentages of exergy losses take place in the gas cooler and compressor. Moreover, heat rejection pressures, outlet temperatures of gas cooler and evaporating temperatures have strong influence on the exergy efficiency, COP and the exergy loss of each component. The analysis shows that there exists an optimal heat rejection pressure corresponding to the maximum exergy efficiency and COP, respectively. The results are of significance in providing theoretical basis for optimal design and the control of the transcritical carbon dioxide system with an expansion turbine. 相似文献
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吕圣杰 《商丘职业技术学院学报》2010,9(2):78-81
根据多家电厂水水换热器的实际应用调查,将各种指标进行深度对比得出：水质污染较为严重、水流量较大或者水阻压降较小的闭式循环冷却水系统适宜选用管式换热器;反之,宜选择板式换热器． 相似文献
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根据工程热力学、传热学、热工测试技术等关于换热器性能的基本测试原理和方法,结合现行的国家标准与规范要求,研发了水源热泵用换热器综合实验台.该实验台利用控制与测量技术,采用被测换热器与辅助换热器水侧部分的冷热负荷,通过水-水板式热交换器相互抵消方法,以及换热器两侧热平衡工作原理,即换热器水侧吸收或放出的热量与制冷剂侧放出或吸收的热量基本相等,可以实现在不同工况下对不同结构形式的R22蒸发器及冷凝器的换热性能和流体阻力性能进行全面的测试.为换热器的选型、优化设计和新产品开发提供依据和验证手段. 相似文献
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Configuration Consideration for Expander in Transcritical Carbon Dioxide Two-Stage Compression Cycle
To investigate the configuration consideration of expander in transcritical carbon dioxide two-stage compression cycle, the best place in the cycle should be searched for to reinvest the recovery work so as to improve the system efficiency. The expander and the compressor are connected to the same shaft and integrated into one unit, with the latter being driven by the former,thus the transfer loss and leakage loss can be decreased greatly. In these systems, the expander can be either connected with the first stage compressor ( shortened as DCDL cycle) or the second stage compressor ( shortened as DCDH cycle), but the two configuration ways can get different performances. By setting up theoretical model for two kinds of expander configuration ways in the transcritical carbon dioxide two-stage compression cycle, the first and the second laws of thermodynamics are used to analyze the coefficient of performance, exergy efficiency, inter-stage pressure,discharge temperature and exergy losses of each component for the two cycles. From the model results, the performance of DCDH cycle is better than that of DCDL cycle. The analysis results are indispensable to providing a theoretical basis for practical design and operating. 相似文献
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A novel heat-integrated distillation scheme on pilot scale for producing C5 foaming agent, a mixture of isopentane and pentane in a certain proportion, was proposed with the aid of process simulation. Compared with the conventional distillation scheme, C5 foaming agent was directly separated at the top of the original isopentane or pentane column in the novel scheme, instead of first refining the two isomerides to high purities and then mixing them into final products. This improvement reduced the difficulty of the separation and avoided meaningless exergy loss caused by re-mixing, which finally contributed to an energy-efficient design by a big margin. Moreover, the column grand composite curves(CGCCs)were used to modify all distillation columns, indicating that there is potential to improve the energy efficiency further. Therefore, double-effect, or heat-integrated distillation was also adopted. Energy and exergy analyses were then conducted to evaluate the effectiveness of the proposed scheme for the purpose of energy saving. The simulation results of the conventional distillation scheme were in agreement with its on-site counterpart. Analyses showed that the novel heat-integrated scheme reduced hot utility by 27.12%,, cold utility by 24.49%,, and total exergy loss by 23.95%,. 相似文献